Final answer:
To define an inheritance relationship between a subclass and superclass, the keyword 'extends' is used. 'Implements' is for interfaces, 'super' refers to superclass methods or constructor, and 'SubclassOf' is not a standard keyword.
Step-by-step explanation:
To specify the inheritance relationship between a subclass and a superclass, in the declaration of the subclass, you would use the keyword extends. In object-oriented programming, when creating a subclass that inherits from a superclass, we use 'extends' to indicate that the subclass is deriving its properties and behaviors from the superclass. For example, in Java, if you have a superclass called 'Vehicle' and you want to create a subclass called 'Car', you would write the class declaration for 'Car' as follows:
public class Car extends Vehicle {
// Car class properties and methods
}
It's important to note that 'extends' is used for inheritance in classes, whereas the keyword 'implements' is used when a class wants to implement an interface. The 'super' keyword is used within subclass methods to refer to the superclass methods or constructor, and 'SubclassOf' is not a keyword used in any major programming language for defining inheritance.